It’s one thing to understand the concept of how to do something, it’s another thing altogether to be able to execute.
As an example, I could read books and watch videos on how to operate on a person but no one in their right mind would actually allow me to operate on them. Knowing how to do something and being able to do something are two very different things.
Be careful of assuming that because you know how to do something that you can actually do it.
Have a great day!